Smear Layer Reduction in Root Canals Prepared With Triangular and Rectangular Files as Evaluated by Scanning Electron Microscopy

Abstract

Objective: Root canal preparation procedures can produce a smear layer when in contact with the root canal wall, which can result in treatmentfailure. As such, the cross-section shape of the file may influence the production of smear layer. In this study, we compared the smear layer productionat the apical third of the root canal wall between files with a triangular or rectangular cross-section shape.Methods: Thirty-two human premolar samples taken from mandibles were divided into two groups whose root canals were prepared using fileswith either a triangular (One Curve®, n=16) or rectangular (Hyflex EDM®, n=16) cross-section shape. After preparation, the root canals were irrigatedwith a combination of 2.5% NaOCl and 17% ethylenediaminetetraacetic acid (EDTA). The smear layers in the apical third of the root canal walls wereobserved using a scanning electron microscope and quantified according to the Foschi scoring system.Results: The Mann–Whitney U-test revealed a significant difference between root canal preparations using the different file shapes. The groupprepared with the triangular file produced lower smear layer scores compared with the group prepared with the rectangular file.Conclusion: Root canal preparations using files with different cross-section shapes (e.g., triangular and rectangular), followed by irrigation with 2.5%NaOCl and 17% EDTA, produced smear layers in the apical third area. However, root canal preparations using files with a triangular cross-sectionshape were shown to reduce smear layer production compared with files with a rectangular cross-section shape

Effect of XP-Endo Finisher Rotary File on Removal of Smear Layer on the Root Canal Wall Using Different Rotary Files and Different Irrigants (An Ex- vivo Study)

“…Indeed, there are many ramifications in the apical third of the canal, rendering smear layer removal difficult. 15,18,19 In the current study, the removal of the smear layer at the coronal third was better than at the middle and apical third and there was a lower mean score for the residual smear layer. This can be attributed primarily to the fact that the root canal has a wider diameter at the coronal part, better tissue-chemical contact during instrumentation, and dentin exposure to a larger volume of irrigant.…”

“…Therefore, removing the smear layer is recommended before the root canal obturation process. 11,18,19 The sodium hypochlorite (NaOCl) solution and ethylenediaminetetraacetic acid (EDTA) solution have gained wide acceptance, and their use is advocated as an effective irrigation protocol for smear layer removal. 12,15 These solutions remain the gold standard for endodontic irrigation because of their organic and inorganic matterdissolving activity within the smear layer and antibacterial effect.…”

“…First, both files allow for better negotiation of root canal curvatures, second, the shape of these two files allows for good equalization between smear layer removal and cutting effectiveness. 18,22 In the current study, ×1000 magnification was used because, although high amounts of smear layer can be seen in lower magnifications, the dentinal tubules are only seen at higher magnifications, 21 and higher than ×1000 magnification was not used because higher magnification reduces the observer's field of view. 23,24 The Hűlsmann scoring system, which is credible and reproducible, was utilized to assess the smear layer removal quality.…”

Title: Cleaning ability and Apically Extruded Debris of Three Single file Rotary Nickel Titanium systems (an in vitro study)

“…(25)This is in agreement with a study done to compare italic S-shaped files (MTwo and Reciproc) with a triangular-shaped file (ProTaper) which showed that S-shaped files had better cleaning results. (26) Regarding Extrusion of Debris results, the present study showed that all the extrusion of debris happened with all the tested file systems. That was in acceptance with the studies reviling that no method can totally stop the apically extruded debris.…”

“…This is in agreement with previous studies done. (16,17,22) Apical vapor lock also results in gas entrapment in the apical portion which prevents the instrument from reaching such area. (23) Regarding the results of the Fanta AF F One file in the present study, it might be due to the flat side-cut design offering a better space for the irrigant to be placed during root canal preparation.…”